Jet propulsion boat thrust control system

Abstract

A jet propulsion boat includes: a boat body; a propulsion device that imparts propulsion force to the boat body to propel the boat body; an engine and an electric motor that drive the propulsion device; and a control device that determines which of an engine mode and an electric mode is to be used as an operation mode of driving the propulsion device in accordance with a condition, the engine mode configured to drive the propulsion device with the engine and the electric mode configured to drive the propulsion device with the electric motor while stopping the engine, and controls the engine and the electric motor to drive the propulsion device in the determined operation mode.

The invention claimed is: 
     
         1 . A jet propulsion boat comprising:
 a boat body;   a propulsion device that imparts propulsion force to the boat body to propel the boat body;   an engine and an electric motor that drive the propulsion device;   control circuitry configured to determine which of an engine mode and an electric mode is to be used as an operation mode of driving the propulsion device in accordance with a condition, the engine mode configured to drive the propulsion device with the engine and the electric mode configured to drive the propulsion device with the electric motor while stopping the engine, and controls the engine and the electric motor to drive the propulsion device in the determined operation mode; and   a display mounted on the boat body to display the operation mode that is switched from the engine mode to the electric mode.   
     
     
         2 . The jet propulsion boat according to  claim 1 , wherein:
 the electric motor has maximum output smaller than maximum output of the engine.   
     
     
         3 . The jet propulsion boat according to  claim 1 , wherein the propulsion device includes:
 a first propulsion device that is driven by the engine to impart propulsion force to the boat body, and   a second propulsion device that is driven by the electric motor to impart propulsion force to the boat body, the propulsion force of the second propulsion device being different from the propulsion force imparted to the boat body by the first propulsion device.   
     
     
         4 . The jet propulsion boat according to  claim 3 , wherein:
 the second propulsion device is to impart propulsion force to the boat body, the propulsion force being different in direction from the propulsion force of the first propulsion device.   
     
     
         5 . The jet propulsion boat according to  claim 3 , wherein:
 the second propulsion device is to impart the propulsion force in each of a plurality of directions different from each other to the boat body.   
     
     
         6 . The jet propulsion boat according to  claim 5 , wherein:
 the second propulsion device includes a plurality of thrusters that are each capable of imparting propulsion force different in direction to the boat body, and   the control circuitry adjusts a traveling direction of the boat body by adjusting a magnitude of propulsion force of each of the plurality of thrusters when the propulsion device is driven in the electric mode.   
     
     
         7 . The jet propulsion boat according to  claim 5 , wherein:
 the second propulsion device includes a plurality of thrusters that are each capable of imparting propulsion force different in direction to the boat body, and   the control circuitry adjusts a posture of the boat body by adjusting a magnitude of propulsion force of each of the plurality of thrusters when the propulsion device is driven in the electric mode.   
     
     
         8 . The jet propulsion boat according to  claim 1 , further comprising:
 a falling overboard detector configured to detect that a driver of the jet propulsion boat has fallen into the water,   wherein the control circuitry determines the operation mode to be the electric mode when the falling overboard detector detects that the driver has fallen into the water.   
     
     
         9 . The jet propulsion boat according to  claim 8 , further comprising:
 a falling overboard position detector configured to detect a falling overboard position of the driver,   wherein when the falling overboard detector detects that the driver has fallen into the water, the control circuitry causes the boat body to navigate toward the falling overboard position of the driver detected by the falling overboard position detector in a state where the operation mode is set to the electric mode.   
     
     
         10 . The jet propulsion boat according to  claim 1 , wherein:
 the control circuitry determines the operation mode to be the electric mode when the boat body is requested to be maintained at a fixed position.   
     
     
         11 . The jet propulsion boat according to  claim 1 , wherein:
 the control circuitry determines the operation mode to be the electric mode when the boat body is requested to be moved toward a target position.   
     
     
         12 . The jet propulsion boat according to  claim 1 , wherein:
 the control circuitry determines the operation mode to be the electric mode when the boat body is requested to be changed in posture.   
     
     
         13 . The jet propulsion boat according to  claim 1 , wherein:
 the control circuitry includes area determination circuitry configured to detect whether the boat body is located within a predetermined restriction area, and when the area determination circuitry determines that the boat body is located within the predetermined restriction area, the control circuitry determines the operation mode to be the electric mode.   
     
     
         14 . The jet propulsion boat according to  claim 1 , further comprising:
 an operation interface to interface with a driver of the jet propulsion boat,   wherein the control circuitry determines the operation mode to be the electric mode when a predetermined operation is performed on the operation interface.   
     
     
         15 . The jet propulsion boat according to  claim 1 , further comprising:
 a battery mounted on the boat body to supply power to the electric motor; and   a remaining battery capacity detector configured to detect remaining capacity of the battery,   wherein the control circuitry prohibits switching from the engine mode to the electric mode when the remaining capacity of the battery detected by the remaining battery capacity detector is equal to or less than predetermined determination capacity.   
     
     
         16 . A jet propulsion boat comprising:
 a boat body;   a propulsion device that imparts propulsion force to the boat body to propel the boat body;   an engine and an electric motor that drive the propulsion device;   control circuitry configured to determine which of an engine mode and an electric mode is to be used as an operation mode of driving the propulsion device in accordance with a condition, the engine mode configured to drive the propulsion device with the engine and the electric mode configured to drive the propulsion device with the electric motor while stopping the engine, and controls the engine and the electric motor to drive the propulsion device in the determined operation mode; and   a falling overboard detector configured to detect that a driver of the jet propulsion boat has fallen into the water,   wherein the control circuitry determines the operation mode to be the electric mode when the falling overboard detector detects that the driver has fallen into the water.   
     
     
         17 . A jet propulsion boat comprising:
 a boat body;   a propulsion device that imparts propulsion force to the boat body to propel the boat body;   an engine and an electric motor that drive the propulsion device; and   control circuitry configured to determine which of an engine mode and an electric mode is to be used as an operation mode of driving the propulsion device in accordance with a condition, the engine mode configured to drive the propulsion device with the engine and the electric mode configured to drive the propulsion device with the electric motor while stopping the engine, and controls the engine and the electric motor to drive the propulsion device in the determined operation mode, wherein:   the control circuitry includes area determination circuitry configured to detect whether the boat body is located within a predetermined restriction area, and when the area determination circuitry determines that the boat body is located within the predetermined restriction area, the control circuitry determines the operation mode to be the electric mode.